Conditional Access (CA) technology is commonly used to protect the electronic delivery of digital content. Many CA systems include Downloadable CA (DCAS) systems wherein a secure downloader is used to download a security client to a playback device. Examples of DCAS systems are described in U.S. Pat. Nos. 5,787,172 and 6,456,716 to Arnold, and in U.S. Pat. No. 7,383,438 to Fahrny.
An increasing problem for operators of content distribution systems is the use of illegal duplicate playback devices or clones to access content via the content distribution system. Cloning is typically performed by completely replicating devices or at least replicating information that the system uses to identify a playback device, such as but not limited to a serial number and a media access control (MAC) address. Cloned devices are typically able to operate undetected, because the individual information that the clone has is registered with a legitimate consumer and access from several cloned devices appears to be access from a single legal device to the system.
In one-way networks (e.g. cable or satellite) the cloning of devices is focused on the decryption logic and decryption keys that are used in one legal device. In such a network, all cloned playback devices are able to consume the same content that the original device can consume, and all cloned playback devices will receive key updates and new decryption permissions in the same way.
Potential clones can be detected by observing suspicious patterns of STB behavior of e.g. content consumption or network access. Another method of detecting clones is described in United States Patent Publication No. 2007/0174472 entitled “Network Security System and Method” to Kulakowski et al.